The present invention relates to a pneumatic tire, more particularly to a sidewall structure being capable of improving durability.
In recent years, low profile tires whose aspect ratio is less than 60% are widely used. Especially, in the very low profile tires used in high-performance sport cars, passenger cars, etc., the aspect ratio reaches to 35% or less.
In such a low profile tire, as shown in FIG. 4, as the tire section height is low, the height of the turnup (a2) of the carcass (a) becomes relatively high, and the edge (e) of the carcass turnup (a2) approaches the tire shoulder region (d) or upper sidewall portion (c) which are subjected to a large bending deformation during running. As a result, the possibility of carcass ply edge separation due to stress concentration on the edge (e) increases.
It is therefore, an object of the present invention to provide a pneumatic tire in which the carcass ply edge separation is effectively prevented to improve the durability.
According to the present invention, a pneumatic tire is provided which comprises
a tread portion,
a pair of sidewall portions,
a pair of bead portions each with a bead core therein,
a carcass comprising a carcass main extending from the bead core in one of the bead portions to the bead core in the other bead portion, and a pair of carcass turnups axially outside the carcass main,
a tread rubber disposed in the tread portion,
a sidewall rubber disposed in each of the sidewall portions, and
a wing rubber interposed between the tread rubber and sidewall rubber, wherein
each carcass turnup extends from the axially outside of the bead core to a point in the sidewall portion,
while extending from the axially outside of the bead core to the point in the sidewall portion, the carcass turnup approaches the carcass main and adjoins the carcass main from a first radial height to a second radial height and then separates from the carcass main from the second radial height so as to form a separating part,
the wing rubber has a JIS type-A durometer hardness of from 45 to 60 degrees, and a radially inner part of the wing rubber is inserted between the separating part and the carcass main.